1 /* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) 5 * Michal Wronski (michal.wronski@gmail.com) 6 * 7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul (manfred@colorfullife.com) 10 * 11 * Audit: George Wilson (ltcgcw@us.ibm.com) 12 * 13 * This file is released under the GPL. 14 */ 15 16 #include <linux/capability.h> 17 #include <linux/init.h> 18 #include <linux/pagemap.h> 19 #include <linux/file.h> 20 #include <linux/mount.h> 21 #include <linux/namei.h> 22 #include <linux/sysctl.h> 23 #include <linux/poll.h> 24 #include <linux/mqueue.h> 25 #include <linux/msg.h> 26 #include <linux/skbuff.h> 27 #include <linux/netlink.h> 28 #include <linux/syscalls.h> 29 #include <linux/audit.h> 30 #include <linux/signal.h> 31 #include <linux/mutex.h> 32 33 #include <net/sock.h> 34 #include "util.h" 35 36 #define MQUEUE_MAGIC 0x19800202 37 #define DIRENT_SIZE 20 38 #define FILENT_SIZE 80 39 40 #define SEND 0 41 #define RECV 1 42 43 #define STATE_NONE 0 44 #define STATE_PENDING 1 45 #define STATE_READY 2 46 47 /* used by sysctl */ 48 #define FS_MQUEUE 1 49 #define CTL_QUEUESMAX 2 50 #define CTL_MSGMAX 3 51 #define CTL_MSGSIZEMAX 4 52 53 /* default values */ 54 #define DFLT_QUEUESMAX 256 /* max number of message queues */ 55 #define DFLT_MSGMAX 10 /* max number of messages in each queue */ 56 #define HARD_MSGMAX (131072/sizeof(void*)) 57 #define DFLT_MSGSIZEMAX 8192 /* max message size */ 58 59 60 struct ext_wait_queue { /* queue of sleeping tasks */ 61 struct task_struct *task; 62 struct list_head list; 63 struct msg_msg *msg; /* ptr of loaded message */ 64 int state; /* one of STATE_* values */ 65 }; 66 67 struct mqueue_inode_info { 68 spinlock_t lock; 69 struct inode vfs_inode; 70 wait_queue_head_t wait_q; 71 72 struct msg_msg **messages; 73 struct mq_attr attr; 74 75 struct sigevent notify; 76 struct pid* notify_owner; 77 struct user_struct *user; /* user who created, for accounting */ 78 struct sock *notify_sock; 79 struct sk_buff *notify_cookie; 80 81 /* for tasks waiting for free space and messages, respectively */ 82 struct ext_wait_queue e_wait_q[2]; 83 84 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 85 }; 86 87 static const struct inode_operations mqueue_dir_inode_operations; 88 static const struct file_operations mqueue_file_operations; 89 static struct super_operations mqueue_super_ops; 90 static void remove_notification(struct mqueue_inode_info *info); 91 92 static spinlock_t mq_lock; 93 static struct kmem_cache *mqueue_inode_cachep; 94 static struct vfsmount *mqueue_mnt; 95 96 static unsigned int queues_count; 97 static unsigned int queues_max = DFLT_QUEUESMAX; 98 static unsigned int msg_max = DFLT_MSGMAX; 99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 100 101 static struct ctl_table_header * mq_sysctl_table; 102 103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 104 { 105 return container_of(inode, struct mqueue_inode_info, vfs_inode); 106 } 107 108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 109 struct mq_attr *attr) 110 { 111 struct inode *inode; 112 113 inode = new_inode(sb); 114 if (inode) { 115 inode->i_mode = mode; 116 inode->i_uid = current->fsuid; 117 inode->i_gid = current->fsgid; 118 inode->i_blocks = 0; 119 inode->i_mtime = inode->i_ctime = inode->i_atime = 120 CURRENT_TIME; 121 122 if (S_ISREG(mode)) { 123 struct mqueue_inode_info *info; 124 struct task_struct *p = current; 125 struct user_struct *u = p->user; 126 unsigned long mq_bytes, mq_msg_tblsz; 127 128 inode->i_fop = &mqueue_file_operations; 129 inode->i_size = FILENT_SIZE; 130 /* mqueue specific info */ 131 info = MQUEUE_I(inode); 132 spin_lock_init(&info->lock); 133 init_waitqueue_head(&info->wait_q); 134 INIT_LIST_HEAD(&info->e_wait_q[0].list); 135 INIT_LIST_HEAD(&info->e_wait_q[1].list); 136 info->messages = NULL; 137 info->notify_owner = NULL; 138 info->qsize = 0; 139 info->user = NULL; /* set when all is ok */ 140 memset(&info->attr, 0, sizeof(info->attr)); 141 info->attr.mq_maxmsg = DFLT_MSGMAX; 142 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 143 if (attr) { 144 info->attr.mq_maxmsg = attr->mq_maxmsg; 145 info->attr.mq_msgsize = attr->mq_msgsize; 146 } 147 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 148 mq_bytes = (mq_msg_tblsz + 149 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 150 151 spin_lock(&mq_lock); 152 if (u->mq_bytes + mq_bytes < u->mq_bytes || 153 u->mq_bytes + mq_bytes > 154 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 155 spin_unlock(&mq_lock); 156 goto out_inode; 157 } 158 u->mq_bytes += mq_bytes; 159 spin_unlock(&mq_lock); 160 161 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 162 if (!info->messages) { 163 spin_lock(&mq_lock); 164 u->mq_bytes -= mq_bytes; 165 spin_unlock(&mq_lock); 166 goto out_inode; 167 } 168 /* all is ok */ 169 info->user = get_uid(u); 170 } else if (S_ISDIR(mode)) { 171 inc_nlink(inode); 172 /* Some things misbehave if size == 0 on a directory */ 173 inode->i_size = 2 * DIRENT_SIZE; 174 inode->i_op = &mqueue_dir_inode_operations; 175 inode->i_fop = &simple_dir_operations; 176 } 177 } 178 return inode; 179 out_inode: 180 make_bad_inode(inode); 181 iput(inode); 182 return NULL; 183 } 184 185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 186 { 187 struct inode *inode; 188 189 sb->s_blocksize = PAGE_CACHE_SIZE; 190 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 191 sb->s_magic = MQUEUE_MAGIC; 192 sb->s_op = &mqueue_super_ops; 193 194 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 195 if (!inode) 196 return -ENOMEM; 197 198 sb->s_root = d_alloc_root(inode); 199 if (!sb->s_root) { 200 iput(inode); 201 return -ENOMEM; 202 } 203 204 return 0; 205 } 206 207 static int mqueue_get_sb(struct file_system_type *fs_type, 208 int flags, const char *dev_name, 209 void *data, struct vfsmount *mnt) 210 { 211 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 212 } 213 214 static void init_once(void *foo, struct kmem_cache * cachep, unsigned long flags) 215 { 216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 217 218 inode_init_once(&p->vfs_inode); 219 } 220 221 static struct inode *mqueue_alloc_inode(struct super_block *sb) 222 { 223 struct mqueue_inode_info *ei; 224 225 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 226 if (!ei) 227 return NULL; 228 return &ei->vfs_inode; 229 } 230 231 static void mqueue_destroy_inode(struct inode *inode) 232 { 233 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 234 } 235 236 static void mqueue_delete_inode(struct inode *inode) 237 { 238 struct mqueue_inode_info *info; 239 struct user_struct *user; 240 unsigned long mq_bytes; 241 int i; 242 243 if (S_ISDIR(inode->i_mode)) { 244 clear_inode(inode); 245 return; 246 } 247 info = MQUEUE_I(inode); 248 spin_lock(&info->lock); 249 for (i = 0; i < info->attr.mq_curmsgs; i++) 250 free_msg(info->messages[i]); 251 kfree(info->messages); 252 spin_unlock(&info->lock); 253 254 clear_inode(inode); 255 256 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 257 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 258 user = info->user; 259 if (user) { 260 spin_lock(&mq_lock); 261 user->mq_bytes -= mq_bytes; 262 queues_count--; 263 spin_unlock(&mq_lock); 264 free_uid(user); 265 } 266 } 267 268 static int mqueue_create(struct inode *dir, struct dentry *dentry, 269 int mode, struct nameidata *nd) 270 { 271 struct inode *inode; 272 struct mq_attr *attr = dentry->d_fsdata; 273 int error; 274 275 spin_lock(&mq_lock); 276 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 277 error = -ENOSPC; 278 goto out_lock; 279 } 280 queues_count++; 281 spin_unlock(&mq_lock); 282 283 inode = mqueue_get_inode(dir->i_sb, mode, attr); 284 if (!inode) { 285 error = -ENOMEM; 286 spin_lock(&mq_lock); 287 queues_count--; 288 goto out_lock; 289 } 290 291 dir->i_size += DIRENT_SIZE; 292 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 293 294 d_instantiate(dentry, inode); 295 dget(dentry); 296 return 0; 297 out_lock: 298 spin_unlock(&mq_lock); 299 return error; 300 } 301 302 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 303 { 304 struct inode *inode = dentry->d_inode; 305 306 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 307 dir->i_size -= DIRENT_SIZE; 308 drop_nlink(inode); 309 dput(dentry); 310 return 0; 311 } 312 313 /* 314 * This is routine for system read from queue file. 315 * To avoid mess with doing here some sort of mq_receive we allow 316 * to read only queue size & notification info (the only values 317 * that are interesting from user point of view and aren't accessible 318 * through std routines) 319 */ 320 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 321 size_t count, loff_t * off) 322 { 323 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 324 char buffer[FILENT_SIZE]; 325 size_t slen; 326 loff_t o; 327 328 if (!count) 329 return 0; 330 331 spin_lock(&info->lock); 332 snprintf(buffer, sizeof(buffer), 333 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 334 info->qsize, 335 info->notify_owner ? info->notify.sigev_notify : 0, 336 (info->notify_owner && 337 info->notify.sigev_notify == SIGEV_SIGNAL) ? 338 info->notify.sigev_signo : 0, 339 pid_nr(info->notify_owner)); 340 spin_unlock(&info->lock); 341 buffer[sizeof(buffer)-1] = '\0'; 342 slen = strlen(buffer)+1; 343 344 o = *off; 345 if (o > slen) 346 return 0; 347 348 if (o + count > slen) 349 count = slen - o; 350 351 if (copy_to_user(u_data, buffer + o, count)) 352 return -EFAULT; 353 354 *off = o + count; 355 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 356 return count; 357 } 358 359 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 360 { 361 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 362 363 spin_lock(&info->lock); 364 if (task_tgid(current) == info->notify_owner) 365 remove_notification(info); 366 367 spin_unlock(&info->lock); 368 return 0; 369 } 370 371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 372 { 373 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 374 int retval = 0; 375 376 poll_wait(filp, &info->wait_q, poll_tab); 377 378 spin_lock(&info->lock); 379 if (info->attr.mq_curmsgs) 380 retval = POLLIN | POLLRDNORM; 381 382 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 383 retval |= POLLOUT | POLLWRNORM; 384 spin_unlock(&info->lock); 385 386 return retval; 387 } 388 389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 390 static void wq_add(struct mqueue_inode_info *info, int sr, 391 struct ext_wait_queue *ewp) 392 { 393 struct ext_wait_queue *walk; 394 395 ewp->task = current; 396 397 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 398 if (walk->task->static_prio <= current->static_prio) { 399 list_add_tail(&ewp->list, &walk->list); 400 return; 401 } 402 } 403 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 404 } 405 406 /* 407 * Puts current task to sleep. Caller must hold queue lock. After return 408 * lock isn't held. 409 * sr: SEND or RECV 410 */ 411 static int wq_sleep(struct mqueue_inode_info *info, int sr, 412 long timeout, struct ext_wait_queue *ewp) 413 { 414 int retval; 415 signed long time; 416 417 wq_add(info, sr, ewp); 418 419 for (;;) { 420 set_current_state(TASK_INTERRUPTIBLE); 421 422 spin_unlock(&info->lock); 423 time = schedule_timeout(timeout); 424 425 while (ewp->state == STATE_PENDING) 426 cpu_relax(); 427 428 if (ewp->state == STATE_READY) { 429 retval = 0; 430 goto out; 431 } 432 spin_lock(&info->lock); 433 if (ewp->state == STATE_READY) { 434 retval = 0; 435 goto out_unlock; 436 } 437 if (signal_pending(current)) { 438 retval = -ERESTARTSYS; 439 break; 440 } 441 if (time == 0) { 442 retval = -ETIMEDOUT; 443 break; 444 } 445 } 446 list_del(&ewp->list); 447 out_unlock: 448 spin_unlock(&info->lock); 449 out: 450 return retval; 451 } 452 453 /* 454 * Returns waiting task that should be serviced first or NULL if none exists 455 */ 456 static struct ext_wait_queue *wq_get_first_waiter( 457 struct mqueue_inode_info *info, int sr) 458 { 459 struct list_head *ptr; 460 461 ptr = info->e_wait_q[sr].list.prev; 462 if (ptr == &info->e_wait_q[sr].list) 463 return NULL; 464 return list_entry(ptr, struct ext_wait_queue, list); 465 } 466 467 /* Auxiliary functions to manipulate messages' list */ 468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 469 { 470 int k; 471 472 k = info->attr.mq_curmsgs - 1; 473 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 474 info->messages[k + 1] = info->messages[k]; 475 k--; 476 } 477 info->attr.mq_curmsgs++; 478 info->qsize += ptr->m_ts; 479 info->messages[k + 1] = ptr; 480 } 481 482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 483 { 484 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 485 return info->messages[info->attr.mq_curmsgs]; 486 } 487 488 static inline void set_cookie(struct sk_buff *skb, char code) 489 { 490 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 491 } 492 493 /* 494 * The next function is only to split too long sys_mq_timedsend 495 */ 496 static void __do_notify(struct mqueue_inode_info *info) 497 { 498 /* notification 499 * invoked when there is registered process and there isn't process 500 * waiting synchronously for message AND state of queue changed from 501 * empty to not empty. Here we are sure that no one is waiting 502 * synchronously. */ 503 if (info->notify_owner && 504 info->attr.mq_curmsgs == 1) { 505 struct siginfo sig_i; 506 switch (info->notify.sigev_notify) { 507 case SIGEV_NONE: 508 break; 509 case SIGEV_SIGNAL: 510 /* sends signal */ 511 512 sig_i.si_signo = info->notify.sigev_signo; 513 sig_i.si_errno = 0; 514 sig_i.si_code = SI_MESGQ; 515 sig_i.si_value = info->notify.sigev_value; 516 sig_i.si_pid = current->tgid; 517 sig_i.si_uid = current->uid; 518 519 kill_pid_info(info->notify.sigev_signo, 520 &sig_i, info->notify_owner); 521 break; 522 case SIGEV_THREAD: 523 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 524 netlink_sendskb(info->notify_sock, 525 info->notify_cookie, 0); 526 break; 527 } 528 /* after notification unregisters process */ 529 put_pid(info->notify_owner); 530 info->notify_owner = NULL; 531 } 532 wake_up(&info->wait_q); 533 } 534 535 static long prepare_timeout(const struct timespec __user *u_arg) 536 { 537 struct timespec ts, nowts; 538 long timeout; 539 540 if (u_arg) { 541 if (unlikely(copy_from_user(&ts, u_arg, 542 sizeof(struct timespec)))) 543 return -EFAULT; 544 545 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 546 || ts.tv_nsec >= NSEC_PER_SEC)) 547 return -EINVAL; 548 nowts = CURRENT_TIME; 549 /* first subtract as jiffies can't be too big */ 550 ts.tv_sec -= nowts.tv_sec; 551 if (ts.tv_nsec < nowts.tv_nsec) { 552 ts.tv_nsec += NSEC_PER_SEC; 553 ts.tv_sec--; 554 } 555 ts.tv_nsec -= nowts.tv_nsec; 556 if (ts.tv_sec < 0) 557 return 0; 558 559 timeout = timespec_to_jiffies(&ts) + 1; 560 } else 561 return MAX_SCHEDULE_TIMEOUT; 562 563 return timeout; 564 } 565 566 static void remove_notification(struct mqueue_inode_info *info) 567 { 568 if (info->notify_owner != NULL && 569 info->notify.sigev_notify == SIGEV_THREAD) { 570 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 571 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 572 } 573 put_pid(info->notify_owner); 574 info->notify_owner = NULL; 575 } 576 577 static int mq_attr_ok(struct mq_attr *attr) 578 { 579 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 580 return 0; 581 if (capable(CAP_SYS_RESOURCE)) { 582 if (attr->mq_maxmsg > HARD_MSGMAX) 583 return 0; 584 } else { 585 if (attr->mq_maxmsg > msg_max || 586 attr->mq_msgsize > msgsize_max) 587 return 0; 588 } 589 /* check for overflow */ 590 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 591 return 0; 592 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 593 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 594 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 595 return 0; 596 return 1; 597 } 598 599 /* 600 * Invoked when creating a new queue via sys_mq_open 601 */ 602 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 603 int oflag, mode_t mode, struct mq_attr __user *u_attr) 604 { 605 struct mq_attr attr; 606 int ret; 607 608 if (u_attr) { 609 ret = -EFAULT; 610 if (copy_from_user(&attr, u_attr, sizeof(attr))) 611 goto out; 612 ret = -EINVAL; 613 if (!mq_attr_ok(&attr)) 614 goto out; 615 /* store for use during create */ 616 dentry->d_fsdata = &attr; 617 } 618 619 mode &= ~current->fs->umask; 620 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 621 dentry->d_fsdata = NULL; 622 if (ret) 623 goto out; 624 625 return dentry_open(dentry, mqueue_mnt, oflag); 626 627 out: 628 dput(dentry); 629 mntput(mqueue_mnt); 630 return ERR_PTR(ret); 631 } 632 633 /* Opens existing queue */ 634 static struct file *do_open(struct dentry *dentry, int oflag) 635 { 636 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 637 MAY_READ | MAY_WRITE }; 638 639 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 640 dput(dentry); 641 mntput(mqueue_mnt); 642 return ERR_PTR(-EINVAL); 643 } 644 645 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 646 dput(dentry); 647 mntput(mqueue_mnt); 648 return ERR_PTR(-EACCES); 649 } 650 651 return dentry_open(dentry, mqueue_mnt, oflag); 652 } 653 654 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 655 struct mq_attr __user *u_attr) 656 { 657 struct dentry *dentry; 658 struct file *filp; 659 char *name; 660 int fd, error; 661 662 error = audit_mq_open(oflag, mode, u_attr); 663 if (error != 0) 664 return error; 665 666 if (IS_ERR(name = getname(u_name))) 667 return PTR_ERR(name); 668 669 fd = get_unused_fd(); 670 if (fd < 0) 671 goto out_putname; 672 673 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 674 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 675 if (IS_ERR(dentry)) { 676 error = PTR_ERR(dentry); 677 goto out_err; 678 } 679 mntget(mqueue_mnt); 680 681 if (oflag & O_CREAT) { 682 if (dentry->d_inode) { /* entry already exists */ 683 audit_inode(name, dentry->d_inode); 684 error = -EEXIST; 685 if (oflag & O_EXCL) 686 goto out; 687 filp = do_open(dentry, oflag); 688 } else { 689 filp = do_create(mqueue_mnt->mnt_root, dentry, 690 oflag, mode, u_attr); 691 } 692 } else { 693 error = -ENOENT; 694 if (!dentry->d_inode) 695 goto out; 696 audit_inode(name, dentry->d_inode); 697 filp = do_open(dentry, oflag); 698 } 699 700 if (IS_ERR(filp)) { 701 error = PTR_ERR(filp); 702 goto out_putfd; 703 } 704 705 set_close_on_exec(fd, 1); 706 fd_install(fd, filp); 707 goto out_upsem; 708 709 out: 710 dput(dentry); 711 mntput(mqueue_mnt); 712 out_putfd: 713 put_unused_fd(fd); 714 out_err: 715 fd = error; 716 out_upsem: 717 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 718 out_putname: 719 putname(name); 720 return fd; 721 } 722 723 asmlinkage long sys_mq_unlink(const char __user *u_name) 724 { 725 int err; 726 char *name; 727 struct dentry *dentry; 728 struct inode *inode = NULL; 729 730 name = getname(u_name); 731 if (IS_ERR(name)) 732 return PTR_ERR(name); 733 734 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 735 I_MUTEX_PARENT); 736 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 737 if (IS_ERR(dentry)) { 738 err = PTR_ERR(dentry); 739 goto out_unlock; 740 } 741 742 if (!dentry->d_inode) { 743 err = -ENOENT; 744 goto out_err; 745 } 746 747 inode = dentry->d_inode; 748 if (inode) 749 atomic_inc(&inode->i_count); 750 751 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 752 out_err: 753 dput(dentry); 754 755 out_unlock: 756 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 757 putname(name); 758 if (inode) 759 iput(inode); 760 761 return err; 762 } 763 764 /* Pipelined send and receive functions. 765 * 766 * If a receiver finds no waiting message, then it registers itself in the 767 * list of waiting receivers. A sender checks that list before adding the new 768 * message into the message array. If there is a waiting receiver, then it 769 * bypasses the message array and directly hands the message over to the 770 * receiver. 771 * The receiver accepts the message and returns without grabbing the queue 772 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 773 * are necessary. The same algorithm is used for sysv semaphores, see 774 * ipc/sem.c for more details. 775 * 776 * The same algorithm is used for senders. 777 */ 778 779 /* pipelined_send() - send a message directly to the task waiting in 780 * sys_mq_timedreceive() (without inserting message into a queue). 781 */ 782 static inline void pipelined_send(struct mqueue_inode_info *info, 783 struct msg_msg *message, 784 struct ext_wait_queue *receiver) 785 { 786 receiver->msg = message; 787 list_del(&receiver->list); 788 receiver->state = STATE_PENDING; 789 wake_up_process(receiver->task); 790 smp_wmb(); 791 receiver->state = STATE_READY; 792 } 793 794 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 795 * gets its message and put to the queue (we have one free place for sure). */ 796 static inline void pipelined_receive(struct mqueue_inode_info *info) 797 { 798 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 799 800 if (!sender) { 801 /* for poll */ 802 wake_up_interruptible(&info->wait_q); 803 return; 804 } 805 msg_insert(sender->msg, info); 806 list_del(&sender->list); 807 sender->state = STATE_PENDING; 808 wake_up_process(sender->task); 809 smp_wmb(); 810 sender->state = STATE_READY; 811 } 812 813 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 814 size_t msg_len, unsigned int msg_prio, 815 const struct timespec __user *u_abs_timeout) 816 { 817 struct file *filp; 818 struct inode *inode; 819 struct ext_wait_queue wait; 820 struct ext_wait_queue *receiver; 821 struct msg_msg *msg_ptr; 822 struct mqueue_inode_info *info; 823 long timeout; 824 int ret; 825 826 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 827 if (ret != 0) 828 return ret; 829 830 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 831 return -EINVAL; 832 833 timeout = prepare_timeout(u_abs_timeout); 834 835 ret = -EBADF; 836 filp = fget(mqdes); 837 if (unlikely(!filp)) 838 goto out; 839 840 inode = filp->f_path.dentry->d_inode; 841 if (unlikely(filp->f_op != &mqueue_file_operations)) 842 goto out_fput; 843 info = MQUEUE_I(inode); 844 audit_inode(NULL, inode); 845 846 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 847 goto out_fput; 848 849 if (unlikely(msg_len > info->attr.mq_msgsize)) { 850 ret = -EMSGSIZE; 851 goto out_fput; 852 } 853 854 /* First try to allocate memory, before doing anything with 855 * existing queues. */ 856 msg_ptr = load_msg(u_msg_ptr, msg_len); 857 if (IS_ERR(msg_ptr)) { 858 ret = PTR_ERR(msg_ptr); 859 goto out_fput; 860 } 861 msg_ptr->m_ts = msg_len; 862 msg_ptr->m_type = msg_prio; 863 864 spin_lock(&info->lock); 865 866 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 867 if (filp->f_flags & O_NONBLOCK) { 868 spin_unlock(&info->lock); 869 ret = -EAGAIN; 870 } else if (unlikely(timeout < 0)) { 871 spin_unlock(&info->lock); 872 ret = timeout; 873 } else { 874 wait.task = current; 875 wait.msg = (void *) msg_ptr; 876 wait.state = STATE_NONE; 877 ret = wq_sleep(info, SEND, timeout, &wait); 878 } 879 if (ret < 0) 880 free_msg(msg_ptr); 881 } else { 882 receiver = wq_get_first_waiter(info, RECV); 883 if (receiver) { 884 pipelined_send(info, msg_ptr, receiver); 885 } else { 886 /* adds message to the queue */ 887 msg_insert(msg_ptr, info); 888 __do_notify(info); 889 } 890 inode->i_atime = inode->i_mtime = inode->i_ctime = 891 CURRENT_TIME; 892 spin_unlock(&info->lock); 893 ret = 0; 894 } 895 out_fput: 896 fput(filp); 897 out: 898 return ret; 899 } 900 901 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 902 size_t msg_len, unsigned int __user *u_msg_prio, 903 const struct timespec __user *u_abs_timeout) 904 { 905 long timeout; 906 ssize_t ret; 907 struct msg_msg *msg_ptr; 908 struct file *filp; 909 struct inode *inode; 910 struct mqueue_inode_info *info; 911 struct ext_wait_queue wait; 912 913 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 914 if (ret != 0) 915 return ret; 916 917 timeout = prepare_timeout(u_abs_timeout); 918 919 ret = -EBADF; 920 filp = fget(mqdes); 921 if (unlikely(!filp)) 922 goto out; 923 924 inode = filp->f_path.dentry->d_inode; 925 if (unlikely(filp->f_op != &mqueue_file_operations)) 926 goto out_fput; 927 info = MQUEUE_I(inode); 928 audit_inode(NULL, inode); 929 930 if (unlikely(!(filp->f_mode & FMODE_READ))) 931 goto out_fput; 932 933 /* checks if buffer is big enough */ 934 if (unlikely(msg_len < info->attr.mq_msgsize)) { 935 ret = -EMSGSIZE; 936 goto out_fput; 937 } 938 939 spin_lock(&info->lock); 940 if (info->attr.mq_curmsgs == 0) { 941 if (filp->f_flags & O_NONBLOCK) { 942 spin_unlock(&info->lock); 943 ret = -EAGAIN; 944 msg_ptr = NULL; 945 } else if (unlikely(timeout < 0)) { 946 spin_unlock(&info->lock); 947 ret = timeout; 948 msg_ptr = NULL; 949 } else { 950 wait.task = current; 951 wait.state = STATE_NONE; 952 ret = wq_sleep(info, RECV, timeout, &wait); 953 msg_ptr = wait.msg; 954 } 955 } else { 956 msg_ptr = msg_get(info); 957 958 inode->i_atime = inode->i_mtime = inode->i_ctime = 959 CURRENT_TIME; 960 961 /* There is now free space in queue. */ 962 pipelined_receive(info); 963 spin_unlock(&info->lock); 964 ret = 0; 965 } 966 if (ret == 0) { 967 ret = msg_ptr->m_ts; 968 969 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 970 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 971 ret = -EFAULT; 972 } 973 free_msg(msg_ptr); 974 } 975 out_fput: 976 fput(filp); 977 out: 978 return ret; 979 } 980 981 /* 982 * Notes: the case when user wants us to deregister (with NULL as pointer) 983 * and he isn't currently owner of notification, will be silently discarded. 984 * It isn't explicitly defined in the POSIX. 985 */ 986 asmlinkage long sys_mq_notify(mqd_t mqdes, 987 const struct sigevent __user *u_notification) 988 { 989 int ret; 990 struct file *filp; 991 struct sock *sock; 992 struct inode *inode; 993 struct sigevent notification; 994 struct mqueue_inode_info *info; 995 struct sk_buff *nc; 996 997 ret = audit_mq_notify(mqdes, u_notification); 998 if (ret != 0) 999 return ret; 1000 1001 nc = NULL; 1002 sock = NULL; 1003 if (u_notification != NULL) { 1004 if (copy_from_user(¬ification, u_notification, 1005 sizeof(struct sigevent))) 1006 return -EFAULT; 1007 1008 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1009 notification.sigev_notify != SIGEV_SIGNAL && 1010 notification.sigev_notify != SIGEV_THREAD)) 1011 return -EINVAL; 1012 if (notification.sigev_notify == SIGEV_SIGNAL && 1013 !valid_signal(notification.sigev_signo)) { 1014 return -EINVAL; 1015 } 1016 if (notification.sigev_notify == SIGEV_THREAD) { 1017 /* create the notify skb */ 1018 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1019 ret = -ENOMEM; 1020 if (!nc) 1021 goto out; 1022 ret = -EFAULT; 1023 if (copy_from_user(nc->data, 1024 notification.sigev_value.sival_ptr, 1025 NOTIFY_COOKIE_LEN)) { 1026 goto out; 1027 } 1028 1029 /* TODO: add a header? */ 1030 skb_put(nc, NOTIFY_COOKIE_LEN); 1031 /* and attach it to the socket */ 1032 retry: 1033 filp = fget(notification.sigev_signo); 1034 ret = -EBADF; 1035 if (!filp) 1036 goto out; 1037 sock = netlink_getsockbyfilp(filp); 1038 fput(filp); 1039 if (IS_ERR(sock)) { 1040 ret = PTR_ERR(sock); 1041 sock = NULL; 1042 goto out; 1043 } 1044 1045 ret = netlink_attachskb(sock, nc, 0, 1046 MAX_SCHEDULE_TIMEOUT, NULL); 1047 if (ret == 1) 1048 goto retry; 1049 if (ret) { 1050 sock = NULL; 1051 nc = NULL; 1052 goto out; 1053 } 1054 } 1055 } 1056 1057 ret = -EBADF; 1058 filp = fget(mqdes); 1059 if (!filp) 1060 goto out; 1061 1062 inode = filp->f_path.dentry->d_inode; 1063 if (unlikely(filp->f_op != &mqueue_file_operations)) 1064 goto out_fput; 1065 info = MQUEUE_I(inode); 1066 1067 ret = 0; 1068 spin_lock(&info->lock); 1069 if (u_notification == NULL) { 1070 if (info->notify_owner == task_tgid(current)) { 1071 remove_notification(info); 1072 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1073 } 1074 } else if (info->notify_owner != NULL) { 1075 ret = -EBUSY; 1076 } else { 1077 switch (notification.sigev_notify) { 1078 case SIGEV_NONE: 1079 info->notify.sigev_notify = SIGEV_NONE; 1080 break; 1081 case SIGEV_THREAD: 1082 info->notify_sock = sock; 1083 info->notify_cookie = nc; 1084 sock = NULL; 1085 nc = NULL; 1086 info->notify.sigev_notify = SIGEV_THREAD; 1087 break; 1088 case SIGEV_SIGNAL: 1089 info->notify.sigev_signo = notification.sigev_signo; 1090 info->notify.sigev_value = notification.sigev_value; 1091 info->notify.sigev_notify = SIGEV_SIGNAL; 1092 break; 1093 } 1094 1095 info->notify_owner = get_pid(task_tgid(current)); 1096 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1097 } 1098 spin_unlock(&info->lock); 1099 out_fput: 1100 fput(filp); 1101 out: 1102 if (sock) { 1103 netlink_detachskb(sock, nc); 1104 } else if (nc) { 1105 dev_kfree_skb(nc); 1106 } 1107 return ret; 1108 } 1109 1110 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1111 const struct mq_attr __user *u_mqstat, 1112 struct mq_attr __user *u_omqstat) 1113 { 1114 int ret; 1115 struct mq_attr mqstat, omqstat; 1116 struct file *filp; 1117 struct inode *inode; 1118 struct mqueue_inode_info *info; 1119 1120 if (u_mqstat != NULL) { 1121 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1122 return -EFAULT; 1123 if (mqstat.mq_flags & (~O_NONBLOCK)) 1124 return -EINVAL; 1125 } 1126 1127 ret = -EBADF; 1128 filp = fget(mqdes); 1129 if (!filp) 1130 goto out; 1131 1132 inode = filp->f_path.dentry->d_inode; 1133 if (unlikely(filp->f_op != &mqueue_file_operations)) 1134 goto out_fput; 1135 info = MQUEUE_I(inode); 1136 1137 spin_lock(&info->lock); 1138 1139 omqstat = info->attr; 1140 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1141 if (u_mqstat) { 1142 ret = audit_mq_getsetattr(mqdes, &mqstat); 1143 if (ret != 0) 1144 goto out; 1145 if (mqstat.mq_flags & O_NONBLOCK) 1146 filp->f_flags |= O_NONBLOCK; 1147 else 1148 filp->f_flags &= ~O_NONBLOCK; 1149 1150 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1151 } 1152 1153 spin_unlock(&info->lock); 1154 1155 ret = 0; 1156 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1157 sizeof(struct mq_attr))) 1158 ret = -EFAULT; 1159 1160 out_fput: 1161 fput(filp); 1162 out: 1163 return ret; 1164 } 1165 1166 static const struct inode_operations mqueue_dir_inode_operations = { 1167 .lookup = simple_lookup, 1168 .create = mqueue_create, 1169 .unlink = mqueue_unlink, 1170 }; 1171 1172 static const struct file_operations mqueue_file_operations = { 1173 .flush = mqueue_flush_file, 1174 .poll = mqueue_poll_file, 1175 .read = mqueue_read_file, 1176 }; 1177 1178 static struct super_operations mqueue_super_ops = { 1179 .alloc_inode = mqueue_alloc_inode, 1180 .destroy_inode = mqueue_destroy_inode, 1181 .statfs = simple_statfs, 1182 .delete_inode = mqueue_delete_inode, 1183 .drop_inode = generic_delete_inode, 1184 }; 1185 1186 static struct file_system_type mqueue_fs_type = { 1187 .name = "mqueue", 1188 .get_sb = mqueue_get_sb, 1189 .kill_sb = kill_litter_super, 1190 }; 1191 1192 static int msg_max_limit_min = DFLT_MSGMAX; 1193 static int msg_max_limit_max = HARD_MSGMAX; 1194 1195 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1196 static int msg_maxsize_limit_max = INT_MAX; 1197 1198 static ctl_table mq_sysctls[] = { 1199 { 1200 .ctl_name = CTL_QUEUESMAX, 1201 .procname = "queues_max", 1202 .data = &queues_max, 1203 .maxlen = sizeof(int), 1204 .mode = 0644, 1205 .proc_handler = &proc_dointvec, 1206 }, 1207 { 1208 .ctl_name = CTL_MSGMAX, 1209 .procname = "msg_max", 1210 .data = &msg_max, 1211 .maxlen = sizeof(int), 1212 .mode = 0644, 1213 .proc_handler = &proc_dointvec_minmax, 1214 .extra1 = &msg_max_limit_min, 1215 .extra2 = &msg_max_limit_max, 1216 }, 1217 { 1218 .ctl_name = CTL_MSGSIZEMAX, 1219 .procname = "msgsize_max", 1220 .data = &msgsize_max, 1221 .maxlen = sizeof(int), 1222 .mode = 0644, 1223 .proc_handler = &proc_dointvec_minmax, 1224 .extra1 = &msg_maxsize_limit_min, 1225 .extra2 = &msg_maxsize_limit_max, 1226 }, 1227 { .ctl_name = 0 } 1228 }; 1229 1230 static ctl_table mq_sysctl_dir[] = { 1231 { 1232 .ctl_name = FS_MQUEUE, 1233 .procname = "mqueue", 1234 .mode = 0555, 1235 .child = mq_sysctls, 1236 }, 1237 { .ctl_name = 0 } 1238 }; 1239 1240 static ctl_table mq_sysctl_root[] = { 1241 { 1242 .ctl_name = CTL_FS, 1243 .procname = "fs", 1244 .mode = 0555, 1245 .child = mq_sysctl_dir, 1246 }, 1247 { .ctl_name = 0 } 1248 }; 1249 1250 static int __init init_mqueue_fs(void) 1251 { 1252 int error; 1253 1254 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1255 sizeof(struct mqueue_inode_info), 0, 1256 SLAB_HWCACHE_ALIGN, init_once, NULL); 1257 if (mqueue_inode_cachep == NULL) 1258 return -ENOMEM; 1259 1260 /* ignore failues - they are not fatal */ 1261 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1262 1263 error = register_filesystem(&mqueue_fs_type); 1264 if (error) 1265 goto out_sysctl; 1266 1267 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1268 error = PTR_ERR(mqueue_mnt); 1269 goto out_filesystem; 1270 } 1271 1272 /* internal initialization - not common for vfs */ 1273 queues_count = 0; 1274 spin_lock_init(&mq_lock); 1275 1276 return 0; 1277 1278 out_filesystem: 1279 unregister_filesystem(&mqueue_fs_type); 1280 out_sysctl: 1281 if (mq_sysctl_table) 1282 unregister_sysctl_table(mq_sysctl_table); 1283 kmem_cache_destroy(mqueue_inode_cachep); 1284 return error; 1285 } 1286 1287 __initcall(init_mqueue_fs); 1288